The Humble Bundle Batman: Arkham Origins and South Park: Stick of Truth.runs from May 7 to May 21, and offers daily flash sales as well as longer-lasting discounts. Games on offer include relatively recent titles like
Arkham Origins is probably the best value for money right now, available for £6.89 from a regular price of £22.99. There are several other good deals, including the fantasy puzzle title Trine for just £0.69.
In true Steam sale style, it's probably a good idea to keep an eye on the website for the latest deals in case one of them takes your fancy.